There's about a dozen layers of nuance that need to be addressed before we advocate for all million or so military members to rise up against presidents (or congressional representatives, or judiciaries, or...)

The first of which is the definition of "enemy."

It's a huge fucking stretch to expect individual soldiers to be able to declare who is or is not an enemy when you're not under imminent danger or protecting any critical assets. Supervising officers largely do not make that decision, as they're focused on a specific near-term tasking set. Unit commanders largely do not make that decision, as they're focused on meshing tactical warfare requirements with the administrative and logistical burdens needed for a competent force. Even combatant commanders largely do not make that decision, as they fight for resources and posture their chess pieces to be able to respond in SHTF situations. The same way we do not expect US Naval ships facing harassment from Iranian rocket boats on a daily basis to decide that "today's the day" and start a war with Iran is how important this distinction is and why it's not an easy ask.

The military needs an actual order, coming from some combination of the Secretary of Defense and the National Security Council in order to define enemies and engage in combat. Congress (should) officially declare enemies of the United States. There is some current debate on if the US needs to officially declare "enemies" in order to add gravity to some charges like treason, but my understanding is that China is no more an enemy of the US than Russia is. Another way of saying that is the US might not be friendly towards some, but is not willing to declare those countries as explicit enemies. It's hard to perform effective diplomacy with another entity if you've already announced that you cannot coexist peacefully.

Thus, expecting the military to rise up against a president is expecting them to jump every level in the chain of command and take on the impossible decision of deciding what's in the United States' best interest themselves. I think that's generally considered a shitty take.